Re: [Boost-users] Best way to create a class usingthe singletonpattern and shared pointers?

From: Stephen Torri (storri_at_[hidden])
Date: 2007-05-17 11:18:39

On Thu, 2007-05-17 at 16:59 +0200, Leon Mlakar wrote:
> > Now I am trying to be a good programmer and keep track of my pointers.
> > So I decided that I should replace the pointer with a shared_ptr.
> > 
> > In regards to the validity of calling get() on an unassigned 
> > shared_ptr I thought that if a shared_ptr was declared in the 
> > header and no call is given to any constructor that the 
> > default constructor would be used.
> > Therefore the shared_ptr would have a value of 0x0.
> 
> It would, and you shouldn't get the message. Perhaps the message comes from
> the copy assignment (which again, it shouldn't) - try
> 
> 	m_instance.reset(new Trace_State());
> 
> instead.
> 
> You could also simply write if (!m_instance) as shared_ptr declares operator
> ! just for this purpose.
> 
> But I agree, in a singleton pattern you benefit from shared pointer only if
> the singleton lives shorter than the application and you want to make sure
> it's not gone while still in use.
> 
> Leon

Since its suppose to live the length of the application then its alright
that we make it follow the Meyers Singleton without using the boost
shared_ptr. Thanks for the help.

Stephen